When the plunger rises to the "upper point" and then moves down, the inclined groove of the plunger will meet the suction port again, and the hydraulic oil will be sucked into the plunger sleeve again, repeating the above action again.

Oil pump displacement

Control electronic control state: The control hydraulic signals related to the displacement change are the oil flow of the front pump, the oil flow of the rear pump, the pilot oil and the negative flow. The oil flow of the front and rear pumps directly controls the oil pump, and the pilot oil is throttled by the electric proportional valve. Controlling the oil pump, we can call it the pilot secondary pressure. Let's take the pump control as an example to analyze the change of displacement.

control element

Spool valve: It is a three-position three-way valve, which is composed of a valve core and a sliding sleeve, and the two can move relative to each other. The movement of the spool is balanced by the primary piston and the secondary piston at the right end of the spool and the spring at the left end of the spool. The movement of the sliding sleeve is controlled by the swash plate piston, and moves with the movement of the swash plate piston, and its moving distance and direction are consistent with the swash plate piston.